Organic electroluminescence generating devices

ABSTRACT

An electroluminescence generating device comprising e. a channel of organic semiconductor material, said channel being able to carry both types of charge carriers, said charge carriers being electrons and holes; f. an electron electrode, said electron electrode being in contact with said channel and positioned on top of a first side of said channel layer or within said channel layer, said electron electrode being able to inject electrons in said channel layer; g. a hole electrode, said hole electrode being spaced apart from said electron electrode, said hole electrode being in contact with said channel and positioned on top of said first side of said channel layer or within said channel layer, said hole electrode being able to inject holes into said channel; h. a control electrode positioned on said first side or on a second side of said channel; whereby light emission of said electroluminescence generating device can be acquired by applying an electrical potential difference between said electron electrode and said hole electrode.

FIELD OF THE INVENTION

The present invention is related to the field of organic and polymerelectronics, more specifically it is related to the field of organiclight-emitting devices.

BACKGROUND OF THE INVENTION

Organic electroluminescence generating devices are typically fabricatedby sandwiching one or more organic layers between conductive electrodes.Upon application of an electric field, negative charges are injectedinto the organic layer or organic layers from one electrode, andpositive charges are injected into the organic layer or organic layersfrom the other electrode. Injected charges travel across the organiclayer or organic layers until when they radiatively recombine to emitlight.

Examples of prior art organic electroluminescence generating devices arevertical stacks of organic layers sandwiched between two electrodes asillustrated in FIG. 1. An alternate example of prior art organicelectroluminescence generating devices comprises three electrode deviceswhere conductive electrodes injecting negative and positive charges intothe organic layers are vertically displaced and separated by one or moreorganic layers. Injected charges travel across the vertical stack oforganic layers until they radiatively recombine to emit light. Anillustrative example of such structure is shown in FIG. 2.

The vertical displacement of the charge injecting electrodes requiresthat charge carriers travel across organic layers thereby limitingcharge carriers mobility. It is known in the art that charge carriermobilities in most organic thin films are significantly higher in aplane parallel to the substrate than in a direction perpendicular to thesubstrate, when these planes correspond to deposited organic layers.

AIM OF THE INVENTION

An aim of the present invention is to provide novel electroluminescencegenerating devices which advantageously combines charge carriersmobility occurring in a plane parallel to the substrate, thereby takingfull advantage of the higher in-plane charge carriers mobility,simplified device fabrication with simultaneous fabrication of chargeinjecting electrodes, and electrical characteristics controlled by thecontrolling electrode.

This aim and other aims that will become apparent from the followingdisclosure are reached by the electroluminescence generating devices ofthe present invention, comprising a thin layer, that is further referredto as the channel, comprising at least one layer of an organicsemiconductor, and three or more electrodes. At least one electrode issuitable for injecting one type of charge carriers (e.g. holes), atleast one electrode is suitable for injecting the other type of chargecarriers (e.g. electrons) and at least one electrode, that will bereferred to as the controlling electrode, is suitable to control thecharge injection and/or the charge recombination within the channeland/or the current flow between at least two of the above electrodes.The electrodes for injecting one type of charge carriers (e.g. holes)into the channel and the electrodes for injecting the other type ofcharge carriers (e.g. electrons) into the channel are preferablypositioned in an essentially horizontal plane along the channel. Thecontrolling electrode is preferably separated from the organicsemiconductor by a dielectric layer. The injected charge carriers ofopposite sign recombine radiatively to generate light. An illustrativeview of a light-emitting device of the present invention is illustratedin FIG. 3.

SUMMARY OF THE INVENTION

The present invention provides an electroluminescence generating devicecomprising:

-   -   a. a channel of organic semiconductor material, the channel        being able to carry both types of charge carriers, the charge        carriers being electrons and holes;    -   b. an electron electrode, the electron electrode being in        contact with the channel and positioned on top of a first side        of the channel layer or within the channel layer, the electron        electrode being able to inject electrons in the channel layer;    -   c. a hole electrode, the hole electrode being spaced apart from        the electron electrode, the hole electrode being in contact with        the channel and positioned on top of the first side of the        channel layer or within the channel layer, the hole electrode        being able to inject holes into the channel;    -   d. a control electrode positioned on the first side or on a        second side of the channel;        whereby light emission of the electroluminescence generating        device can be acquired by applying an electrical potential        difference between the electron electrode and the hole        electrode.

Advantageously the electroluminescence generating device comprisesfurther a dielectric layer between the channel and the controlelectrode.

This dielectric layer preferably comprises at least one materialselected from the group consisting of silicon oxide, alumina, polyimideand polymethylmetacrylate

In preferred embodiments at least one of the electron electrode and thehole electrode comprises at least one different material which is notcomprised in the other one.

The electron electrode preferably comprises one or more elementsselected from the group consisting of Au, Ca, Mg, Al, In, PerovskiteManganites (Re_(1−x)A_(x)MnO₃).

Preferably the hole electrode comprises at least one material selectedfrom the group consisting of Au, indium tin oxide, Cr, Cu, Fe, Ag,poly(3,4-ethylenedioxythiophene) combined with poly(styrene sulfonate),Perovskite Manganites (Re_(1−x)A_(x)MnO₃).

The channel can comprise at least one material selected from the groupconsisting of small molecule materials, polymers and metal complexes.

Advantageously the channel comprises at least one material selected fromthe group consisting of tetracene, pentacene, perylenes, terthiophene,tetrathiophene, quinquethiophene, sexithiophene, bora-diazaindacene,polyphenylenevinylene, polyfluorene, polythiophene and porphyrins.

In certain embodiments according to the present invention, the channelcomprises an amorphous semiconductor material

In other embodiments the channel comprises a poly-crystallinesemiconductor material

In advantageous embodiments, the channel comprising poly-crystallinesemiconductor material has a crystal grain size and the hole electrodeand the electron electrode are spaced apart at a distance smaller thenthe grain size.

Advantageously the hole electrode and the electron electrode are spacedapart at a distance between 5 nm and 5 microns.

In certain embodiments according to the present invention, leading tohigher light-output per device, electron electrode and the holeelectrode have digitated structures comprising a regular repetition of abasic finger structure, and are positioned such that the basic fingerstructures of respectively hole and electron electrodes are alternatingeach other, and is characterised by two in-plane distances P and Rbetween the basic finger structures.

Advantageously the distances P and R are equal.

In certain embodiments the control electrode is an injection controlelectrode, the injection control electrode being positioned on thesecond side of the channel, whereby the application of an electricalpotential difference between the control electrode and the holeelectrode or electron electrode, facilitates the injection of chargecarriers into the channel.

In other embodiments the control electrode is a current controlelectrode, the current control electrode being positioned on the secondside of the channel, whereby the application of an electrical potentialdifference between the control electrode and the electron and/or holeelectrode allows to control the current of at least one type of chargecarriers.

The channel can comprise more then one sublayers.

In certain embodiments, the channel comprises an electron injection typesublayer, able to facilitate injection of electrons, a hole injectiontype sublayer, able to facilitate injection of holes, and arecombination type sublayer, able to facilitate recombination of thecharge carriers.

The devices according to the present invention can further compriseoptical confinement and/or waveguiding layers on the first and/or thesecond side of the channel.

The devices according to the present invention can further compriseoptical resonating structures or cavities on the first and/or the secondside of the channel.

The devices according to this invention can comprise a flexible or rigidsubstrate.

The channel can be formed by sublimation of small molecules.

The channel can be formed by simultaneous sublimation of at least twomoieties.

The channel can also be formed by solution processing of one or moresoluble and/or polymeric materials.

The channel can also be formed by a combination of sublimation andsolution processing

This channel can be formed by thermal, chemical or physical treatment ofpre-deposited organic semiconductors.

It can also be manufactured with printing techniques.

The devices according to the present invention make optimal use of amethod for generating electroluminescence, by recombination of electronsand holes injected in the channel from the electron electrode and holeelectrode.

They advantageously combine the fact of higher charge carrier mobilitieswhen occurring in a plane parallel to the substrate. The devices areeasy to fabricate. At least one controlling electrode is present tocontrol the electrical and light-emission characteristics of thelight-emitting device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross section view of a prior art light-emitting device withtwo electrodes, wherein A is a cathode electrode, B is an organiclight-emitting layer, C is an organic semiconductor layer, D is a holeinjection layer, E is an anode electrode and F is a glass substrate.

FIG. 2 is a cross section view of a prior art light-emitting device withthree electrodes, wherein G is a cathode electrode, H is an organiclight-emitting layer, I is an organic semiconductor transport layer, Lis a source electrode, M is a gate dielectric layer, N is a transparentgate electrode and O is a glass substrate.

FIG. 3 is a cross section view of an electroluminescence generatingdevice of the present invention, wherein 1 is a substrate, 2 is acontrolling electrode, 3 is a dielectric layer, 4 is a channelcomprising layers of organic semiconductors, 5 is a hole injectingelectrodes, 6 is an electron injecting electrodes, 7 iselectroluminescence.

FIG. 4 is a graph illustrating the current between electrodes 5 and 6and the corresponding generated electroluminescence as a function of thevoltage between electrodes 5 and 6 for a constant voltage betweenelectrodes 2 and 6 of the electroluminescence generating device of FIG.3 in the case when the current of one type of charge carriers (holes inFIG. 4) dominates over the current of the other type of charge carriers(electrons in FIG. 4).

FIG. 5 is a graph illustrating the current between electrodes 5 and 6and the corresponding generated electroluminescence as a function of thevoltage between electrodes 2 and 6 for a constant voltage betweenelectrodes 5 and 6 of the electroluminescence generating device of FIG.3 in the case when the current of one type of charge carriers (holes inFIG. 5) dominates over the current of the other type of charge carriers(electrons in FIG. 5).

FIG. 6 is a graph illustrating the current between electrodes 5 and 6(Top) and the corresponding generated electroluminescence (Bottom) as afunction of the voltage between electrodes 5 and 6 for a constantvoltage between electrodes 2 and 6 of the electroluminescence generatingdevice of FIG. 3 in the case when the device is operated in ambipolarmode, i.e. simultaneous p- and n-channels are formed. For negative biasbetween electrodes 2 and 6, typical p-channel characteristics areobserved when the bias between electrodes 5 and 6 is negative and theabsolute value of the voltage between electrodes 5 and 6 is smaller orequal to the absolute value of the voltage between electrodes 2 and 6.Increasing the absolute value of the voltage between electrodes 5 and 6,the current between electrodes 5 and 6 increases due to electroninjection in the device and ambipolar operation. Similarly, for positivebias between electrodes 2 and 6, typical n- channel characteristics areobserved when the bias between electrodes 5 and 6 is positive and thevalue of the voltage between electrodes 5 and 6 is smaller or equal tothe value of the voltage between electrodes 2 and 6. Increasing thevalue of the voltage between electrodes 5 and 6, the current betweenelectrodes 5 and 6 increases due to hole injection in the device andambipolar operation.

FIG. 7 is a photograph of the top view of an electroluminescent deviceaccording to the present invention, showing electrode fingers. Fingers‘5’ are the hole-injecting electrodes of FIG. 3, and are made of Au.Fingers ‘6’ are the electron-injecting electrodes of FIG. 3 and are madeof Ca. In the area in between the fingers is the electroluminescentorganic material. The controlling electrode ‘2’ of FIG. 3 is not visiblein FIG. 7, as it is covered by a gate dielectric and by the structuresvisible in the photograph.

FIG. 8 is a photograph similar to FIG. 7 but with a largermagnification, showing Au fingers ‘5’ and Ca fingers ‘6’, with tetraceneorganic material in the channel between the finger contacts.

FIG. 9.a is a detail picture of an alternating interdigitized structureof calcium and gold contacts. The organic semiconductor material on topof these contacts is tetracene. FIG. 9.b is the negative image oflight-emission from the tetracene layer in this structure when thecontacts are voltage-biased according to the measurement shown in FIG.11.

FIG. 10 represents a measurement on a device structure with alternatinggold and calcium injection contacts deposited on the silicon oxidesurface layer of a silicon substrate. The silicon substrate ismetallized with aluminum, which serves as a controlling electrode. Theelectrode numbering is according to the one used in FIG. 3.

FIG. 11 is a schematic representation of a possible injection mechanismof electrons from an injecting electrode to an organic layer, driven bythe voltage applied between electrodes 5 and 6 of FIG. 3. The largeelectric field at the injecting contact induces a local distortion ofthe organic material electronic levels (Lowest Unoccupied MolecularOrbital (LUMO) (8) and Highest Occupied Molecular Orbital (HOMO) (9)levels) that facilitates charge carriers injection (electrons (e⁻) inFIG. 11) via a tunneling process from the Fermi level (E_(F)) of theinjecting electrode to the level 8 of the organic material.

MODES FOR CARRYING OUT THE INVENTION

In a preferred embodiment the device has three electrodes. A firstelectrode is suitable for injecting one type of charge carriers (e.g.holes), a second electrode is suitable for injecting the other type ofcharge carriers (e.g. electrons) and a third controlling electrode issuitable to control the charge injection, the charge recombination andthe current flow between the first and the second electrodes. Thecontrolling electrode is preferably separated from the semiconductor bya dielectric layer. The injected charge carriers of opposite signrecombine radiatively to generate light.

In another embodiment the device has at least two controllingelectrodes. In one embodiment one controlling electrode can be used tocontrol the current flow of one type of charge carriers and anothercontrolling electrode can be used to control the current flow of theother type of charge carriers.

In another embodiment one controlling electrode is used to control theinjection of one type of the charge carriers and a second controllingelectrode is used to control the injection of the other type of thecharge carriers.

In another embodiment one controlling electrode is used to control thespatial distribution of one type of the injected charge carriers and asecond controlling electrode is used to control the spatial distributionof the other type of the injected charge carriers.

In another embodiment one controlling electrode is used to control thecurrent flows and a second controlling electrode is used to control thelocation of the charge carrier recombination zone within the organicsemiconductor layer.

A controlling electrode can be used to control the injection of a typeof charge carriers.

In another embodiment the electrodes which act as carrier injectionelectrode can be integrated in an interdigitated structure where onetype of electrode, which injects one type of carriers, is alternated inspace with the electrode which injects the opposed type of carriers. Apurely illustrative example of such structure is represented in FIG. 7,where gold and calcium electrodes are alternatingly repeated. The devicein FIG. 7 consists of a silicon substrate with silicon oxide on top. Ina first step of a process for manufacturing such a device, the goldelectrodes are vacuum deposited by metal evaporation through a shadowmask. Secondly, the calcium electrodes are deposited similarly throughanother shadow mask. Then a tetracene layer is deposited by vacuumdeposition. The aluminum metal on the backside of the silicon substrateserves as controlling electrode. The carrier injection electrodes (heregold and calcium) can be situated beneath an active organic layer orabove it. The performance of such device in terms of charge carriertransport and light-emission will be optimized if the distances from onetype of electrode to its two electrodes adjacent (given by P and R inFIG. 8) are equal.

The injection of electrons and holes in the above structure is importantfor the functioning of the device. Injection of charge carriers can bemediated by impurities and hetero-species. Impurities and hetero-speciescan act to form a staircase of energy levels that facilitate chargeinjection into the channel. The incorporation in the channel ofimpurities and hetero-species can therefore be used to facilitate theinjection of one or both types of charge carriers. Examples ofimpurities are atoms, ions, molecules different from the main moiety ofthe channel. Also doping atoms or molecules can be used as suchimpurities. Prior art shows that doping atoms or molecules introduced ina semiconductor undergo an ionisation process and leave a chargedparticle (atom or molecule) that changes the potential distribution,which effect can be used to facilitate injection of a type of carriersinto a semiconductor.

Other means to facilitate charge carrier injection include the use of alarge electric field at the injecting contact. Such favourable field canbe created for instance by the electrode configuration, by the electrodeshape, by the creation of an accumulation of charge carriers. Aschematic representation of the possible role of the electric field inassisting charge carrier injection is shown in FIG. 11.

Charge carrier injection can also be facilitated by the use of amaterial for the injecting electrode that has a low barrier againstinjection of a charge carrier type in a channel of the device. Examplesof materials that can be used to fabricate the injecting electrodes areAu, Ca, Mg, Al, In, Perovskite Manganites (Re_(1−x)A_(x)MnO₃), indiumtin oxide, Cr, Cu, Fe, Ag and poly(3,4-ethylenedioxythiophene) combinedwith poly(styrene sulfonate). Charge carrier injection into the channelcan further be facilitated by interposing one or several layers ofmaterial that form a staircase of electronic levels between the energylevel of the injecting electrode and the energy level required forinjection in a semiconductor.

Charge carrier injection and electroluminescence can also be facilitatedby designing the injection electrodes to fit the morphology of anorganic material which is used as active layer. The morphology isdetermined by the intrinsic property of the organic materials and thedeposition method. The distance between the injection electrodes can besmaller than the average grain size of poly-crystalline films (typicallyin the range of 20 nanometers to 5 micrometers). In such case, carriersof opposite type (electrons and holes) can be injected in one grain bythe electrodes ‘5’ and ‘6’ directly into a single grain of thepoly-crystalline organic semiconductor. As an example, FIG. 9 shows agold metal and calcium electrode adjacent to each other with a distanceof less than one micrometer between them. This list of methods tofacilitate injection of charge carriers is not intended to belimitative, and a person skilled in the art can extend it to moremethods.

An aim of this embodiment of the invention is to provide anelectroluminescence generating device comprising a channel having atleast one layer of an organic semiconductor, at least two electrodes forinjecting two different types of charge carriers, and at least onecontrolling electrode, and a method to facilitate the injection of atleast one type of charge carriers into the channel. The channel of thedevice of the present invention consists of at least one layer oforganic semiconductor. An organic semiconductor can consist of smallmolecules (whereby it is meant molecules that can be processed bysublimation), preferably tetracene, pentacene, perylenes, oligothiophens(terthiophenes, tetrathiophene, quinquethiophene or sexithiophene),bora-diazaindacene fluorophores; it can be a polymer, such aspolyphenylenevinylene, polyfluorene or polythiophene; it can be a metalcomplex such as Pt-octaethylporphyrin. The list of materials is notintended to be limitative, but only to provide examples. The organicsemiconductor used in the channel can consist of small molecules andpolymers, which have been chemically, electrochemically or physicallyprocessed to show n-type (or alternatively p-type) behavior incombination or in place of the p-type (or alternatively n-type)transport characteristics.

In another embodiment, the channel can consist of several layers oforganic semiconductors, each of them with a specific function in thedevice. In an embodiment the channel consists of two layers of organicsemiconductors. In one layer of organic semiconductor the injection andtransport of one type of charge carriers preferentially occurs, in theother layer of organic semiconductor the injection and transport of theother type of charge carriers preferentially occurs. Charges of oppositesign recombine radiatively in one of the two layers of organicsemiconductors or at the interface between them to generate light.

In another embodiment the channel consists of three layers of organicsemiconductors. In one layer of organic semiconductor the injection andtransport of one type of charge carriers preferentially occurs, inanother layer of organic semiconductor the injection and transport ofthe other type of charge carriers preferentially occurs. In the thirdlayer of organic semiconductor or at one of the interfaces between thethird and the other two layers the charges of opposite sign recombineradiatively to generate light.

Organic layers or doping moieties can be inserted in the channel tofacilitate and optimize light emission via, for example, energy transferprocesses from the organic species in which the charges first recombineto the organic layers or doping moieties which act as energy acceptors.The energy transfer process can be used to separate zones within thechannel with high electric fields and high density of free earners fromthe zone where exciton recombination and light emission occurs, whichwould result in improved light emission efficiency of the device.

In another embodiment the channel consist of a co-evaporated layer oftwo or more materials. The materials may have specific charge transport,charge recombination, energy transfer and light emission functions inthe device.

In another embodiment the channel consist of two co-evaporatedmaterials, each acting as a transport mean for one type of chargecarriers in the channel. One type of charge earner is injected in onematerial which is in contact with an injecting electrode and istransported via an interpenetrated path towards the other electrode. Theother type of charge carrier is injected by the other electrode in theother material and is transported via an interpenetrated path towardsthe other electrode. The two types of charges recombine in the channeland generate light emission.

In another embodiment the channel is formed by solution processing apolymer or a polymer blend that creates an interpenetrating network ofp-type and n-type materials.

The channel can further be realized by several coplanar layers oforganic semiconductors, each of them with a specific function (chargeinjection, charge transport, charge recombination, energy transfer andlight emission, just to mention some possible functions) in the device.

The channel can also be realized by a combination of coplanar layers oforganic semiconductors and vertically stacked layers of organicsemiconductors.

Transport of a type of charge carriers through the entire channel maynot be necessary, provided that injected charges into the channelrecombine radiatively with charges of opposite sign to emit light.

Examples of materials for injecting electrodes are gold, calcium,aluminium, magnesium. Examples of dielectrics are silicon dioxide (alsoin its porous form), alumina, polyimide, polymethylmetacrylate. The listof materials is not intended to be limitative, but only to provideexamples.

In a further improvement of the device, optical confinement layers areadded to the device structure below and/or above the channel. Preferredmeans of optical confinement comprise a structure of material with lowerrefractive index than that of the channel, such as to provide opticalconfinement by waveguiding, and a reflector, such as a distributed Braggreflector or a metal mirror.

Depending on the channel characteristics, on the materials used and onthe optical confinement layers, light can be emitted isotropically or inspecific directions or within a specific solid angle.

The device according to the invention can be made in differentconfigurations. In a first configuration, a controlling electrode orcontrolling electrodes are deposited first on a substrate, followed by adielectric, followed by injecting electrodes, followed by a channellayer that comprises an organic semiconductor. In an alternativeembodiment, an injecting electrode is deposited on top of a channel, asshown in FIG. 3. In yet another embodiment, a dielectric and acontrolling electrodes are deposited on top of a channel.

The devices according to the invention are operated by applying a firstappropriate bias voltage to a controlling electrode, and injectingelectrons from a first electrode and holes from a second electrode,while maintaining a second bias voltage between the latter twoelectrodes. The first and second bias voltages can be continuousvoltages. In an alternative operation method, they can also be pulsedvoltages. The devices can be operated at room temperature. Inalternative, they can be operated in the temperature range from 1°Kelvin to 450° Kelvin.

The light output of the device can be perpendicular to the plane of thesubstrate and the layer sequel described above. It can also be guided inthe plane of the substrate, in particular when optical confinementlayers as described above are provided. The light output can beincoherent.

The light output can also be coherent and light output can be laseremission. In an embodiment of lasers based on the above described devicestructure suitable organic semiconductors, optical confinementstructures, optical resonators or cavities are used so to providecoherent light output and lasing.

The device structure of the present invention is compatible with planartechnology and can easily be integrated into electronic andoptoelectronic Integrated Circuits. The potential of nanotechnology, inparticular for down-scaling the relevant device features and fornanostructuring the channel, can be used to optimize and tailor thedevice characteristics.

The use of the above mentioned devices range from nanoscale lightsources for nanophotonics and nano-optoelectronics, optoelectronicIntegrated Circuits, lasers applications, displays, informationtechnologies, ambient and automotive illumination. The potential forapplications, in particular for intense light generation sources, arisesfrom the specific device geometry and working mechanism, which allows tobetter control charge earners injection and to limit the destructiveinteraction of the light-emitting excitons with the charge carriers andthe electric field in the channel. The list of applications andtechnologies is not intended to be limitative, but only to provideexamples.

The disclosures in U.S. Ser. No. 60/458,847 from which this applicationclaims priority are incorporated herein by reference.

1. An electroluminescence generating device comprising: a channelcomprising at least one layer of an organic semiconductor material, saidchannel being able to carry both types of charge carriers, said chargecarriers being electrons and holes; an electron injector electrode, saidelectron injector electrode being in contact with said channel andpositioned on top of a first side of said channel or within saidchannel, said electron injector electrode being able to inject electronsin said channel; a hole injector electrode, said hole injector electrodebeing spaced apart from said electron injector electrode, said holeinjector electrode being in contact with said channel and positioned ontop of a first side of said channel or within said channel, said holeinjector electrode being able to inject holes in said channel, each ofsaid electron injector electrode and said hole injector electrode beingpositioned in an essentially horizontal plane along said channel; and acontrol electrode positioned on said first side or on a second side ofsaid channel, said control electrode being suitable for controlling thecharge injection, the current flow and the charge recombination betweenthe electron injector electrode and the hole injector electrode, saidelectroluminescence generating device being able to emit light byapplying an electrical potential difference between said electroninjector electrode and said hole injector electrode.
 2. The deviceaccording to claim 1, further comprising a dielectric layer between saidchannel and said control electrode.
 3. The device according to claim 2,wherein said dielectric layer comprises at least one material selectedfrom the group consisting of silicon oxide, alumina, polyimide andpolymethylmethacrylate.
 4. The device according to claim 1, wherein saidelectron injector electrode comprises one or more elements selected fromthe group consisting of Au, Ca, Mg, Al, In, and Perovskite Manganites.5. The device according to claim 1, wherein said hole injector electrodecomprises at least one material selected from the group consisting ofAu, indium tin oxide, Cr, Cu, Fe, Ag, poly(3,4-ethylendioxythiophene)combined with poly(styrene sulfonate), and Perovskite Manganites.
 6. Thedevice according to claim 1, wherein said channel comprises at least onematerial selected from the group consisting of small molecule materials,polymers and metal complexes.
 7. The device according to claim 6,wherein said channel comprises at least one material selected from thegroup consisting of tetracene, pentacene, perylenes, terthiophene,tetrathiophene, quinquethiophene, sexithiophene, bora-diazaindacene,polyphenylenevinylene, polyfluorene, polythiophene and porphyrins. 8.The device according to claim 1, wherein said semiconductor organicmaterial is a polycrystalline semiconductor organic material having acrystal grain size and said hole injector electrode and said electroninjector electrode are spaced apart at a distance smaller than saidcrystal grain size.
 9. The device according to claim 1, wherein saidhole injector electrode and said electron injector electrode are spacedapart at a distance between 5 nm and 5 microns.
 10. The device accordingto claim 1, wherein said electron injector electrode and said holeinjector electrode have digitated structures comprising a regularrepetition of a basic finger structure, and are positioned such thatsaid basic finger structures of said basic finger structures ofrespectively hole and electron injector electrodes are alternating eachother, and is characterized by two in-plane distances P and R betweenthe basic finger structures.
 11. The device according to claim 10,wherein said P and R are equal.
 12. The device according to claim 1,wherein said control electrode is an injection control electrode, saidinjection control electrode being positioned on said second side of saidchannel and being suitable to facilitate the injection of chargecarriers into said channel upon the application of an electricalpotential difference between said control electrode and said holeinjector electrode or an electron injector electrode.
 13. The deviceaccording to claim 1, wherein said control electrode is a currentcontrol electrode, said current control electrode being positioned onsaid second side of said channel whereby being suitable for controllingthe current of at least one type of charge carriers upon the applicationof an electrical potential difference between said control electrode andsaid electron and/or hole injector electrode.
 14. The device accordingto claim 1, wherein said channel comprises three layers of organicsemiconductors.
 15. The device according to claim 14, wherein the threelayers of organic semiconductors are: a first electron injection andtransport layer; a second recombination organic semiconductor layer; anda third hole injection and transport organic semiconductor layer
 16. Thedevice according to claim 15, wherein said three layers of organicsemiconductors are coplanar layers of organic semiconductors.
 17. Thedevice according to claim 1, where said at least one layer of organicsemiconductor material are a plurality of coplanar layers of organicsemiconductor material.
 18. The device according to claim 1, furthercomprising optical confinement and/or wave guiding layers on said firstand/or second side of said channel.
 19. The device according to claim18, wherein the optical confinement and/or wave guiding layers have alower refractive index than the refractive index of the channel.
 20. Thedevice according to claim 1, further comprising optical resonatingstructures or cavities on said first and/or second side of said channel.21. The device according to claim 1, further comprising a flexible orrigid substrate.
 22. The device according to claim 1, wherein thecontrol electrode comprises at least two control electrodes.
 23. Thedevice according to claim 1, wherein all the injector electrodes are onthe same first side of the channel opposite to the control electrode onthe second side of the channel.
 24. The device according to claim 1,wherein said electron electrode comprises one or more elements selectedfrom the group consisting of Mg, In, and Perovskite Manganites.
 25. Thedevice according to claim 1, wherein said hole electrode comprises atleast one material selected from the group consisting of indium tinoxide, Fe, Ag, poly(3,4-ethylendioxythiophene) combined withpoly(styrene sulfonate), and Perovskite Manganites.
 26. The deviceaccording to claim 1, further comprising one or more materials forming astaircase of electronic levels between a) an energy level of theelectron injection electrode and/or the hole injection electrode and b)an energy level required for said charge injection into the channel. 27.The device according to claim 26, wherein said one or more materials arein form of layers.